Punching hand-tool



Tuly 9, 1957 Filed Oct. 20,1955

P. LAUNAX PUNCHING HAND-TOO L 2 Sheets-Sheet; 1

PUNCHING HAND-TOOL Pierre Launay, Toulouse, France, assignor toR. K. Price Associates, Inc., New York, N. Y., a company of New York Application Oetober 20', .l95r5',uSeria'l No;- 541,7 87 Claims priority, application France October 25', 1954 3 Claims. 01. 164-121) This invention relates to a hand-operated punchingtool for cutting two opposed notch enlargements of an initial hole in asheet metal or a stifi sheet material by one single Operation eflected from one side only. of the notch;

A further object of the invention is to design the punchingimembers of the tool so that they, may'beguided in r the initial hole during the whole punching operation, which makes the same more accurate.

Still another object of the invention is to make one ofthe cutting members automatically retractable into the nited States Patent other one upon engagement of the latter into the initial hole to permit passingboth cuttingmembers through said hole.

A still further objectof the invention is to design the punching members in such a manner that said retraction may be ensured, ifdesired, merely upon passingsaid members through the hole, normally to the material.

Yet anotherobject of the invention is to providemeans for automatically locking said retractable member in said active position against'any reaction force resulting, from the punching. operation, once both punching members have been passed through said hole.

Preferredembodiments of my invention will be hereinafter described with reference to the accompanying drawings, givenimerely byway of example and in which:

Figure lis a side elevational viewwith parts broken away and partial sections of a hand operated punching tool according to the invention, shown in rest position:

Figure 2-is a view similar to Figural, but 'showingithe tool" inoperated position. 1

Figure 3 is a plane view of the tool shown in Figures 1 and 2.

Figure 4 is a cross-sectional view along line 44 of Figure 1, of the head of the tool.

Figures 5, 6, 7, 8 and 9 are axial sectional views of the head of the tool, showing five different steps of a punching operation.

Figure 10 shows a hole in a sheet metal before and after the cutting of notches with a tool according to the invention.

In all figures, the corresponding elements have been designated by the same reference numbers.

In the example shown in Figures 1 to 3, the handactuation means provided for operating the punching-tool according to the invention are constituted by two hand levers 1 and 2 made of sectional iron and articulated 2,798,555 Fatented July, 9, 1957 2"- together bymeans of a pivot axle. 3 in the fashion ofthe handles of pliers.

In this example, the head ofthe tool is essentiallyconstituted by the active endportion oflever' lwhich, for this. purpose, is provided with a bore 4 (cf. Figures 5 to 8 in whichis reciprocably mountcdthe punching assembly constituted by a first punching member 5 which is hollow and by a second punching member 6 retractable therein. The punching member 5 terminates atits upper end (in the drawings) in an enlarged portion 7 under which bears the suitably crankedact'ive' end of the lever Zsd that when the two levers 1' and 2 are moved towards each other the said leverz is capable, while being brought from the-position sli'ow'n in'Fi'gure 1 to that shown in Figure 2', to move the enlargement 7 and, hence the punching assembmaxiany in a direction' causingretraetion 'ofth'e'punchingfl members into the head of the tool. The arrangement is such that, once the punching men-ib'ers have been passed through a hole such as 12" in a sheet material, aseiiposed hereunder; the said retraction determines, by cooperation withthe head bearing on the material 'in] the vicinity of said hole, the successive ciitt'irig oftwo opposed notches also as showri in Figure 10'. Springnieans 8, fixedly secured -on the lever 2' by means ofa screw 9: continuously urge the reciprocable punching assembly towards itstrest position shown in Figure. 1, iii which it projects out of theheadof the tool'sufli'ciently to be passed "through an initial hole, with said head remainingon"theffront sideofthe material as shown, for example, in Figures 7 and 82 Other" spring means 10 are provided tourge the lever 1 and 2'away from each other towards 'their'restirelative position shown" in Figure 1. A stud-bolt ll'secured, e; g. on the leverarrn 1; acts as an abutnierit'for the'other' lever 2, so as to limit the relative angular displacement of the'two levers towards each other." The retractable" punching? member" 6 is confirm ouslyurged towards 'itsactivepos'ition in which it projects outradially fromthe hollbw punching member 5 by suitable resilient means, positive abutment'means being furthermore'providedto. lock the punching'rnembe'r 6 against retraction; atleasfduring' the. active steps of a punching operation;

In theexample'shown' in Figures 5to 8', the said abut mentmeans'are'constitutedfbva step, 17 adapted to re.- ceivethe'heelofthe punchingmemberfi When said heel'is engagedin' said step, thetp'unching member 6 is positively locked against radial displacement towards the axis of the: punching member 5 as well as against downwards (in Figures 5to2'9') axial displacement with respect to th'e'latter; In the example shown, the resilient means provided to continuously urge the punching member 6 towards its active locked position in steps-17are con stit'uted, itcombination, by, a comp'ression spring 13 urging the punching member 6 downwardly th'r'ough the mushroom 14--15" and-by a leaf-spring 16 tending to shift the punching member 6 radiallyand outwardly as it is pushed downwardly by the mushroom 1 tl5. The combination of these two spring actions should be capable, on the one hand, of bringing the punching member 6 from a radially and axially retracted position, substantially as shown in Figure 6, to its active position in step 17 as shown in Figures 5, 7, 8 and 9 and, on the other hand, of yieldably holding said punching member 6 in said active position.

When notch enlargements of an initial hole such as 12 (Figures 5 and 10) are to be cut out, the tool is first engaged through said hole, the head of the tool being, if necessary, slightly inclined to facilitate the penetration by hooking first the cutting shoulder of the punching member 5 under the back edge of the plate. There is thus obtained a point of hearing, so that, when the tool is brought into normal relative position with respect to the plate (posi- 3 tion shown in Figure 6), the cooperation of this point of bearing with the upward pushing action then exerted on the punching member 6 by the diagonally opposite edge of the hole easily causesunlocking of said member. The end face of the punching member 6 offers the shape of an oblique cam surface, so that an axial force exerted downwardly on the tool head from the position shown in Figure 6 causes both radial and axial further retraction of the punching member 6, which is then easily passed, in turn, through the hole 12. As soon as the cutting shoulder of the punching member comes into registration withthe back edge of the hole 12, the said punching member 6 is brought back into active position in the step 17 under the combined action of springs 13 and 16. If, now, the hand-actuation means, such as the levers 1 and 2 of Figures 1, 2, and 3 are acted upon, the punching assembly 56 is retracted (upwardly'in Figures 5 to 9) into the head of the tool. In the example shown, said head is completed by a die member 18 secured in the enlarged lower end of the bore 4 by means of a gudgeon ring 19, a guiding washer being, furthermore, interposed between the die member 18 and the bottom of the end counterbore of bore 4. The inner edge of the die member 18 and the outer edges of the punching members 5 and 6 are precisely matched with each other to permit the usual punching action under shearing forces exerted on the material to be cut-out, on either side of the same, by cooperation between the die member and the punching members.

It is to be noted that both punching members are provided above their cutting shoulders with restricted portions adapted to cooperate with the edge of the initial hole 12, to guide the punching assembly in said hole during the whole punching operation. As the punching assembly is retracted upwardly, from the position shown in Figure 7 to that shown in Figure 9, the following steps of operation take place. The lower edge of the die member 18 is first brought into contact with the material around the initial hole 12. The left edge of the said hole is then clamped between said die member and the cutting shoulder of the punching member 6 and cut out by shearing action as shown in Figure 8.

It will be pointed out that during this step, the punching member 6 is exclusively subjected to downwards axial forces possibly with a small radial inwards component, so that it remains perfectly locked in the step 17.

The cutting shoulder of the punching member 5 is then brought, in turn, into contact with the lower right edge of the hole 12, and cuts out the second notch by shearing F action in cooperation with the die member 18 as shown in Figure 9. The axial spacing between the two cutting shoulders is preferably chosen at least equal to the maximum thickness of the sheet materials to be punched out, so as to avoid any overlapping between the two separate steps of the punching operation.

In a general manner, while I have, in the above description, disclosed What I deem to be practical and efiicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the' principle of the present invention.

In particular, while I have indicated how the head of the tool may be inclined at first to facilitate its engagement into the initial hole, it is to be noted that the special arrangement of the abutment means 17 and the resilient means 13, and 16 shown in the drawings, permits passing the head of the tool normally through the hole under retraction of the punching member 6.

What is claimed is:

1. A hand-operated punching tool for cutting two opposed notch enlargements of an initial hole in a sheet metal or other stiff sheet material by a single operation from one side only of the material, said tool comprising a head, a die member mounted on said head and adapted to rest on said material in the vicinity of said hole, a first hollow punching member reciprocably mounted in said head and extending past said die member, a second punching member mounted in said first punching member and retractable thereinto from an active position to permit passing said first punching member through said initial hole, resilient means to continuously urge said second punching member towards said active position, abutment means to lock said second punching member in said active position, each one of said punching members having a restricted portion adapted to be accommodated and guided in said hole and a radially projecting cutting shoulder adapted to cooperate with said die member for cutting, by a shearing action, one of the desired notches, the cutting shoulder of said second punching member being spaced axially from that of said first punching mem her, and hand-actuation means adapted to retract said first punching member axially into said head for successively cutting said two notches in cooperation with said die member.

2. A punching hand-tool according to claim 1, wherein said abutment means are constituted by a step formed in said first punching member to receive the heel of said second punching member to thereby lock the same positively against any displacement under reaction forces resulting from said shearing action, said resilient means being adapted to yield under a relative axial force exerted between said two punching members and tending to retract said second punching member axially into said first one.

3. A punching hand-tool according to claim 2, wherein said resilient means comprise a first spring continuously urging said second punching member axially towards said step and a second spring adapted to shift said second punching member radially and outwardly to guide its heel towards said step.

References Cited in the file of this patent UNITED STATES PATENTS 2,114,753 Waner Apr. 19, 1938 2,229,571 Johnson Jan. 21, 1941 2,378,546 Dit Daude June 18, 1945 

